Functions of the mouth- The function of the mouth and its associated structures is to form a receptacle for food, to begin mechanical digestion through chewing (mastication), to swallow food, and to form words in speech. It can also assist the respiratory system in the passage of air.Functions of the esophagus-The epiglottis is the flap of cartilage lying behind the tongue and in front of the entrance to the larynx (voice box). At rest, the epiglottis is upright and allows air to pass through the larynx and into the rest of the respiratory system. During swallowing, it folds back to cover the entrance to the larynx, preventing food and drink from entering the windpipe. The throat contains both an air passage (the wind pipe) and a food passage (the esophagus). If these passages were both open when a person swallowed, air could enter the stomach and food could enter the lungs. Part of the safety hatch that seals off the windpipe is the "epiglottis," a little valve like cartilage, which works with the larynx to act as a lid every time we swallow. The larynx draws upward and forward to close the windpipe. This keeps solid food and liquid out of the respiratory tract. At the end of each swallow, the epiglottis moves up again, the larynx returns to rest, and the flow of air into the windpipe continues. The uvula (Latin for "little grape") is a fleshy piece of muscle, tissue and mucous membrane that hangs down from the palate. It is the part that moves upward when we say, "Ah!" It flips up and helps close off the nasal passages when we swallow. Contrary to the depictions seen in cartoons, the uvula does not vibrate during singing and shouting and, in fact, has nothing to do with the voice. Function of the stomach-A hollow, sac-like organ connected to the esophagus and the duodenum (the first part of the small intestine), the stomach consists of layers of muscle and nerves that continue the breakdown of food which begins in the mouth. It is also a storage compartment, which enables us to eat only two or three meals a day. If this weren't possible, we would have to eat about every twenty minutes. The average adult stomach stretches to hold from two to three pints and produces approximately the same amount of gastric juices every twenty-four hours. The stomach has several functions(1) as a storage bin, holding a meal in the upper portion and releasing it a little at a time into the lower portion for processing; (2) as a food mixer, the strong muscles contract and mash the food into a sticky, slushy mass; (3) as a sterilizing system, where the cells in the stomach produce an acid which kills germs in "bad" food; (4) as a digestive tub, the stomach produces digestive fluid which splits and cracks the chemicals in food to be distributed as fuel for the body. The process of digestion is triggered by the sight, smell or taste of food, so that the stomach is prepared when the food arrives. Every time you pass a bakery shop or smell your mother's good cooking, the body begins a digestive process. If the stomach is not filled, these gastric juices begin eroding the stomach lining itself, so fill 'er up! Functions of the small intestine-If the small intestine were not looped back and forth upon itself, it could not fit into the abdominal space it occupies. It is held in place by tissues which are attached to the abdominal wall and measures eighteen to twenty-three feet in the average adult, which makes it about four times longer than the person is tall. It is a three-part tube of about one and one-half to two inches in diameter and is divided into three sections: (1) the duodenum, a receiving area for chemicals and partially digested food from the stomach; (2) the jejunum, where most of the nutrients are absorbed into the blood and (3) the ileum, where the remaining nutrients are absorbed before moving into the large intestine. The intestines process about 2.5 gallons of food, liquids and bodily waste every day. In order for enough nutrients to be absorbed into the body, it must come in contact with large numbers of intestinal cells which are folded like gathered skirts. Each of these cells contains thousands of tiny finger-like projections called "vile," and each villa contains microscopic "microvillus". In one square inch of small intestine, there are about 20,000 vile and ten billion microvillus. Each villas brings in fresh, oxygenated blood and sends out nutrient-enriched blood. The vile sway constantly to stir up liquefied food and remove the nutrients which can be absorbed and then passed through the membranes of the vile into the blood and lymph vessels. The fatty nutrients go to the lymph vessels, and glucose and amino acids go to the blood and on to the liver. The muscles which encircle this tube constrict about seven to twelve times a minute to move the food back and forth, to churn it, knead it, and to mix it with gastric juices. The small intestine also makes waves which move the food forward, but these are usually weak and infrequent to allow the food to stay in one place until the nutrients can be absorbed. If a toxic substance enters the small intestine, these movements may be strong and rapid to expel the poisons quickly.Functions of the liver-Thirty per cent of the blood pumped through the heart in one minute passes through the body's chemical factory, which is called the liver. The liver cleanses the blood and processes nutritional molecules, which are distributed to the tissues. The liver also receives bright red blood from the lungs, filled with vital oxygen to be delivered to the heart. The only part of the body which receives more blood than the liver is the brain. The liver is located at the top of the abdomen, just below the diaphragm and has two main lobes. It is the largest gland in the body, weighing 2.5 to 3.3 pounds. When we eat, more blood is diverted to the intestines to deal with digestive processes; when not eating, three-fourths of the blood supply to the liver comes from the intestines. It also produces about two and one-half pints of bile in its ducts, which is delivered to the gallbladder through a small tube called the "cystic duct" for storage. "Liver" is probably an appropriate name for this gland, which makes the important decision as to whether incoming substances are useful to the body or whether they are waste. The liver is an extremely important organ and has multiple functions. The liver detoxifies blood cells by mixing them with bile and by chemical alteration to less toxic substances, such as the alteration of ammonia to urea. Many chemical compounds are inactivated by the liver through modification of chemical structures. The liver convert’s glucose to a storage form of energy called glycogen, and can also produce glucose from sugars, starches, and proteins. The liver also synthesizes triglycerides and cholesterol, breaks down fatty acids, and produces plasma proteins necessary for the clotting of blood, such as clotting factors I, III, V, VII, IX and XI. The liver also produces bile salts and excretes bilirubin. A "lily-livered coward" was someone whose liver contained no blood. The Greeks and Romans sacrificed animals to the gods before going into battle. When the liver was examined, if it was healthy and the blood was bright red, a victory was promised; if it was diseased or the blood was pale, defeat was predicted. Functions of the large intestine-The intestines are a long, continuous tube running from the stomach to the anus. Most absorption of nutrients and water happen in the intestines. The intestines include the small intestine, large intestine, and rectum.The small intestine (small bowel) is about 20 feet long and about an inch in diameter. Its job is to absorb most of the nutrients from what we eat and drink. Velvety tissue lines the small intestine, which is divided into the duodenum, jejunum, and ileum.The large intestine (colon or large bowel) is about 5 feet long and about 3 inches in diameter. The colon absorbs water from wastes, creating stool. As stool enters the rectum, nerves there create the urge to defecateFunctions of the pancreas-The pancreas are an organ located in the abdomen. It plays an essential role in converting the food we eat into fuel for the body's cells. The pancreas has two main functions: an exocrine function that helps in digestion and an endocrine function that regulates blood sugar. Basic Anatomy: The pancreas is located behind the stomach and is surrounded by other organs including the small intestine, liver, and spleen. It is about six inches long and is shaped like a flat pear. The wide part, called the head of the pancreas, is positioned toward the center of the abdomen; the middle section is called the neck and the body of the pancreas; the thin end is called the tail and extends to the left side. Several major blood vessels surround the pancreas, the superior mesenteric artery, the superior mesenteric vein, the portal vein and the celiac axis, supplying blood to the pancreas and other abdominal organs.Exocrine Function: The pancreas contains exocrine glands that produce enzymes important to digestion. When food enters the stomach, these pancreatic juices are released into a system of ducts that culminate in the main pancreatic duct. The pancreatic duct joins the common bile duct to form the ampoule of Voter which is located at the first portion of the small intestine, called the duodenum. The common bile duct originates in the liver and the gallbladder and produces another important digestive juice called bile. The pancreatic juices and bile that are released into the duodenum help the body to digest fats, carbohydrates, and proteins.Endocrine Function: The endocrine component of the pancreas consists of islet cells that create and release important hormones directly into the bloodstream. Two of the main pancreatic hormones are insulin, which acts to lower blood sugar, and glucagon, which acts to raise blood sugar. Maintaining proper blood sugar levels is crucial to the functioning of key organs including the brain, liver, and kidneys